Clay's Ark

Just finished Octavia Butler's 'Clay's Ark'. It's the first book in a long time that I have read in a day. Although it figures in her Patternist series, chronologically the third in the saga though published last, it is only very distantly related to the first two ("Wild Seed" and "Mind of my Mind").
To summarise:
In 2021, in an America rapidly spinning out of control, a man and his two teenage daughters driving across the desert, are stopped by two men and taken at gunpoint to a remote ranch. The inhabitants of this farm, though incredibly strong, are all emaciated and seem to be suffering some kind of disease, a disease they are intent on passing on to their abductees. The nature of this disease and the implications it has for the world raise some very unpleasant issues.
It's a tough bit of writing...and reading. Repellent, violent and marvellously told, it is populated with strong, complex characters. You get to care too much about them, forgetting that at least here Butler is an angry God to this near future world. Close to the end there is one scene in particular that is intensely shocking, especially given the investment Butler has won from us in those characters. She uses the reader's emotions as the very substance of the book, with at least one character voicing our concerns throughout. In some ways it takes the feeling I had at the end of reading George Stewart's "Earth Abides" - an ambiguous, nostalgic, but angry sadness - and makes it the general atmosphere of the whole piece.
Butler is a very visual writer and I am constantly thinking how material like this might transfer to the screen. On the face of it this is classic David Cronenberg territory; he has dealt with similar ideas in "Rabid" and "Shivers". Symbiosis, changing values in the face of evolution, the darker side of sexuality, these are constant themes in his work. However, ideas are one thing, humanity and warmth are another and without them this novel would be too much. Much as I admire his work, warmth and emotion are not Cronenberg's strong points, so perhaps this might not be for him. It still might be interesting to see.
Such musings aside, Butler's work stands by itself. It is testing, powerful and very unsettling.